Intersubband Transitions in Ingaas/Inalas Multiple Quantum Wells Grown on Inp Substrate
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INTERSUBBAND TRANSITIONS IN InGaAs/InAlAs MULTIPLE QUANTUM WELLS GROWN ON InP SUBSTRATE. Qiaoying Zhou*, M. O. Manasreh*, B. D. Weaver**, and M. Missous*** * Depart of Electrical & Computer Engineering, The University of New Mexico, Albuquerque, NM 87131-1356. **Naval Research Lab, 4555 Overlook Ave., SW, Washington, DC 20375. *** Department of Electrical Engineering and Electronics, UMIST, P. O. BOX 88, Manchester M60 1QD, England, UK.
ABSTRACT Intersubband transitions in In0.52Ga0.48As/In0.52Al0.48As multiple quantum wells grown on lattice matched InP substrates were investigated using Fourier transform infrared (FTIR) absorption and photoluminescence (FTPL) techniques. The well width was tailored to produce excited states resonant in the conduction band, at the edge of the conduction band, and confined in the quantum wells. Interband transitions were also probed using FTPL and optical absorption techniques. The FTPL spectra show that three interband transitions exist in the quantum well structures with well width larger than 30 Å. The intersubband transitions in this class of quantum wells seem to withstand proton irradiation with doses higher than those used to deplete the intersubband transitions in the GaAs/AlGaAs multiple quantum wells.
INTRODUCTION Interband and intersubband transitions in bulk semiconductor, multiple quantum wells (MQWs), superlattices, and multiple quantum dots have been the subject of many studies (see for example Refs. [1], [2], [3], [4] and [5]) due to the fact that they form the basis for a new generation of low background and high detectivity very long, long and near wavelength infrared (IR) detectors. Additionally, IR detectors have enabled a new and a wide range of applications even though their potential is not fully realized and explored. GaAs/AlGaAs based multiple quantum well structures are the most mature of quantum well structures and have been widely studied for many applications including IR detectors (see for example Refs. [1], [6], [7] and [2]-[4]. Furthermore, these structures have been used in the development of novel high performance multi-color quantum well infrared photodetector (QWIP) for 3-5 µm mid-wavelength infrared and 8-14 µm longwavelength infrared detection and to obtain a better understanding of the basic mechanisms that could be used to optimize the performance of these QWIPs. In case of shorter wavelength applications such as 1.55 and 1.3 µm for optical communication, the GaAs/AlGaAs MQWs may not be able to meet the demand since the conduction band offset is too small for a such wavelength range. Thus, there is a need to investigate different quantum structures with larger conduction band offset. InGaAs/InAlAs MQWs have the potential to be used as possible structures for shorter wavelength applications due to the fact that this system can be tailored with a larger conduction band offset. H6.25.1
In this paper, we report on the optical properties of intersubband transitions in InGaAs/InAlAs MQWs grown on lattice matched InP substrates. Photoluminescence
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